Health Beverages
for the Ages
June 1997 -- Cover Story

By: Stuart Cantor
Contributing Editor

  Nutritional beverages comprise a significant part of our lives, right from the beginning. The cycle starts with infant formulas - a highly complex drink, rich in several key nutrients. As humans age, and their nutritional requirements change, product designers keep pace by developing new and innovative beverages to meet these needs.  Sports beverages, geared for those engaged in physical activities, were specifically designed to offer athletes a quick energy boost while providing electrolytes lost through sweat. When people reach their mid-30s, many look to weight-loss beverages to return their youthful, svelte figures. During the golden years, optimal nutrition and maintaining a healthy, active lifestyle becomes the focus.  Formulating these beverages requires a thorough technical knowledge of the ingredients, of their interactions with each other, and ways they're affected by the processing treatment used. Knowing when, and how, to incorporate an ingredient into a mix also is vital to preserving its functional characteristics. These factors, coupled with an understanding of the preferences and needs of different age groups, result in beverages that appeal to our health-oriented society.In the beginning  Formulating for little ones is big business. Last year's U.S. infant formula industry took in more than $7 billion, according to International Food Ingredients (volume 4, 1996).  The need for high-quality, bioavailable nutrients, as well as the rapid rate of growth occurring during the first few years of life, makes product formulation critical. Due to their importance, infant formulas are heavily regulated by the U.S. Food and Drug Administration (FDA). FDA revised the U.S. Infant Formula Act of 1980 in 1996 (21 CFR 107.50). The act lists specific requirements for 29 nutrients for healthy babies per 100 kcal of formula. It also requires observance of certain quality-control measures. Ingredients for infant formulas must be food grade - either Food Chemical Codex or United States Pharmacopeia.  FDA also allows infant formulas without all required nutrients. This special "exempt" category of medical foods must be properly labeled and is intended for infants with certain medical or dietary problems.  Many health experts agree that, in terms of nutritional value, mother's milk surpasses infant formula. However, many factors make bottle-feeding with formula necessary. Therefore, infant formula manufacturers strive to closely mimic the composition of mother's milk to reap the nutritional benefits.  Mother's milk contains about 7% carbohydrate, as lactose, and derives about 50% of its calories from fat - a caloric percentage similar to cow's milk. However, unlike cow's milk, human milk contains lower protein and mineral levels, allowing for a baby's level of kidney development.  "Different carbohydrates - such as lactose, maltodextrins or corn syrup solids - can be blended together to produce an infant formula having a similar osmolality to human milk and other bodily fluids, about 300 mOsm/kg water," says Robyn Wimberly, R.D., pediatric nutrition specialist, Carnation Nutritional Products, Glendale, CA. "Osmolality is an important measure of fluid and electrolyte balance, and pertains to the number of dissolved particles in solution."  Lactose contributes some flavor and can be used as a bulking agent without greatly increasing a formula's sweetness level. Lactose provides calories in an easily available form. Its slower digestion and absorption (compared to glucose) benefits intestinal calcium, magnesium and zinc absorption.  Numerous ingredients can supply protein. Soy isolates are used in cases such as lactose intolerance and some milk allergies. The actual form is generally dictated by the format (powdered or ready-to-drink (RTD), for example) and the required viscosity, according to Tom Gottemoller, manager, soy protein, dairy foods application, ADM Protein Specialties Division, Decatur, IL. Soy protein can be hydrolyzed to the point that it no longer contains antigens.  However, most infant formulas use dairy proteins. Whey protein is the primary protein found in human milk, so many manufacturers use whey and nonfat dry milk (NFDM). Generally formulas contain whey protein concentrates. Hypoallergenicity is the main reason to use hydrolysates.  A partially hydrolyzed whey protein concentrate can be prepared by chopping the protein up with trypsin to an average of seven amino acids per peptide chain, Wimberly says. The molecules' smaller size makes them more easily recognizable by the infant's gut and easier to digest.  "(However), in order for a whey hydrolysate to be considered truly hypoallergenic, the hydrolysis must proceed until peptides of less than seven amino acids are obtained and all antigenic sites are removed," says Michael Aoun, applications manager, DMV International, Fraser, NY. Peptides in a partial hydrolysate still possess relatively high average molecular weights and might still contain some exposed antigenic sites (amino acids where antibodies bind), which can stimulate a positive immune response.  The sensory profile of the hydrolysate can be quite different from that of the intact protein due to the presence of bitter peptides. "Unless the flavor system is balanced by adjusting the salt, sweetness and pH levels, and using flavors that complement or mask the natural flavor notes imparted by the hydrolysate, consumers may sense an increased perception of saltiness or bitterness," Aoun says.  By utilizing a revolutionary new technique - called "radial flow chromatography"- duplicating the chemistry of milk from mother might soon be a reality.  "This patented process is not only much faster and more efficient, but it is also more cost-effective than traditional methods at fractionating whey proteins to a high degree of purity," says Vinit Saxena, chief executive officer, Sepragen Corporation, Hayward, CA. "The bovine protein fractions that typically cause allergic problems in some sensitive infants can be separated out, and the remaining proteins can be reconstituted in a proportion similar to that of human milk."  Two minor milk proteins - lactoferrin and lactoperoxidase - show promise as powerful antimicrobial agents. Lactoferrin can bind two atoms of iron. This prevents bacterial growth by cutting off the supply of iron. Lactoferrin also disrupts bacterial digestion of carbohydrates, further limiting their growth. Lactoferrin is usually present in human milk at 2.0 to 8.0 g/L, compared to 0.1 g/L lactoferrin in cow's milk. Lactoperoxidase is part of a milk enzyme system that inactivates bacterial enzymes and proteins by cleaving their sulfhydryl groups.  "While these specialized nutrients are currently being added to infant formulas in Europe and Asia, U.S. manufacturers are still evaluating their proposed benefits at this time," says Jacquelyn Paul, director of North American marketing and sales, DMV International, Fraser, NY.  These proteins are susceptible to partial degradation during pasteurization or retorting. However, Aoun says that problem can be overcome by adding them after heat-processing or by adjusting the pH to the protein's optimal stability. Combined with heat, extremes of pH can be especially damaging to a protein's structure.  The next generation of genetically engineered formulas might contain immunity-enhancing milk proteins - such as lactoferrin or antibodies such as the immunoglobulin, secretory IgA, passed to infants through their mothers' milk. The immunoglobulins act by binding to foreign bacteria and viruses and eliminating them from the body.Baby fat  Babies require a fairly high level of dietary lipids, making infancy one of the few times that fat consumption is encouraged. Most commercial formulas contain between 3.5% and 5.5% total lipids, a composition similar to mother's milk.  Fortifying infant formulas with specific essential fatty acids derived from either marine algae or fish oils, such as arachidonic acid (ARA) and docosahexaenoic acid (DHA), is receiving a high level of interest. In 1995, the World Health Organization recommended adding both DHA and ARA to all infant formulas.  Formula supplemented with these fatty acids enjoys increasing popularity in Europe and Asia, but because no one has sought FDA approval for use in infant formulas here, DHA hasn't made inroads in the United States. Currently, some controversy exists in this country as to whether DHA and the related nutrients are necessary, and whether FDA should mandate their addition to standard and premature infant formulas. Formula manufacturers say unanswered questions exist as to the net nutritive effect and the cost-to-benefit relationship of the added ingredients.  Still, if the rest of the world is any indication, these formulas could become popular here.  "Dozens of clinical studies around the world seem to point to a link between intake of DHA and ARA, and improved intelligence and visual acuity in infants," says David Kyle, Ph.D., senior vice president, R&D, Martek Biosciences Corporation, Columbia, MD. "Interestingly, both DHA and ARA are the predominant fatty acids in brain and retinal tissues. Infants are unable to synthesize the DHA and ARA at a fast enough rate to keep pace with their rapidly developing brain."  Martek has developed a triglyceride supplement, containing DHA derived from a marine microalgae, supplemented with microbial ARA. The polyunsaturated fatty acids (PUFAs) are produced as triglyceride oils, blended together and added in small quantities to formula, with DHA at 180 ppm and ARA at 360 ppm. Natural antioxidants, such as (-tocopherol and ascorbyl palmitate, are added. Along with naturally occurring carotenoids, and packaging under nitrogen, they enhance final product stability.  There is currently debate over whether algae-derived PUFAs offer advantages over fish oils. "While fish oils are a good source of DHA, they generally contain little ARA, and can have an objectionable smell and taste," Kyle says, adding that some studies indicate that another fish-oil PUFA, eicosapentaenoic acid (EPA), may result in a decreased growth rate among infants.  But Herb Woolf, Ph.D., technical service manager, BASF Corporation, Mt. Olive, NJ, disagrees: "The product we make specifically for the infant formula industry has very low levels of EPA, which is felt in most academic circles not to have any negative effects on infants. Different fish species can be selected to provide a more balanced and beneficial fatty-acid profile. High-quality fish oils have negligible taste and smell, and can also be microencapsulated with added antioxidants to improve their stability and prevent off-flavors from developing. BASF also has other products that are specifically designed to deliver ARA to allow customers to formulate with the exact ratios they deem appropriate for the product."Formulating for endurance  Isotonic beverages (or sports drinks) replace fluids, electrolytes and carbohydrates used up during physical activity. These drinks are formulated so that these ingredients nearly match concentrations existing in bodily fluids. Other nutrients, such as bioactive peptides, can be added to help increase energy levels and boost performance.  "The ideal level of total carbohydrates in these beverages is 6%, and more is not necessarily better," says Craig Horswill, Ph.D., research scientist, Gatorade Company, Chicago, IL. "At levels above 6%, the body's active transport mechanism is overloaded. Fluid absorption will be impeded and the muscles will not be able to utilize the additional energy supplied to them." Because fructose is absorbed slower than glucose, beverages using high levels of fructose can cause gastric distress before or during exercise.  Using different carbohydrates varies the sweetness level and functional properties, according to Celeste Sullivan, applications scientist at Grain Processing Corporation, Muscatine, IA.  "A 10 to 18 DE maltodextrin is typically used for sports beverages," Sullivan says, "because it provides a higher caloric density than dextrose, and its higher molecular weight helps keep solution osmolality lower, and thus, similar to body fluids." Since water balance is critically important to athletes, a high-osmolality drink would cause water to be diverted to the intestines to dilute the solutes present, and away from the muscles, where it's needed most.  "Although both supply 4 kcal/g and are easily digestible, because maltodextrins are highly soluble glucose polymers, more energy can be formulated into a drink per serving using them, as opposed to simple sugars," Sullivan says.  Dextrose equivalent (DE) is a quantitative measure of the degree of starch hydrolysis, with starch possessing a DE of zero and dextrose having a DE of 100. The higher the DE, the lower the molecular weight.  Sports drinks contain electrolytes, such as sodium chloride and sodium or potassium salts of citric or phosphoric acid. "The presence of low levels of sodium, (110 mg/8 oz.), assists in rehydrating the body better than water alone, by turning on the osmotic thirst drive which helps the athlete maintain body fluids by promoting fluid intake," Horswill says. Citrates and phosphates act as buffers to maintain the beverage pH, provide a pleasant tart taste, and aid in sequestering metal ions. Levels often are adjusted for taste and label considerations.  Glutamine peptide (derived from the enzymatic hydrolysis of wheat gluten) reportedly increases endurance during exercise, and prevents fatigue due to overtraining. During stress, glutamine is considered as a "conditionally essential" amino acid. This peptide can be added to drinks from 1% to 2%, according to Aoun, and offers the advantages of being completely soluble, very stable throughout a wide pH and temperature range, and has very low bitterness, which can be masked with an appropriate flavorant.  Other amino acids important in athletic performance are the branched-chain amino acids: leucine, isoleucine and valine. Soy and whey proteins provide rich sources of branched-chain amino acids (18 to 26 grams per 100 grams of protein), which provide a direct energy source to muscles during exercise and prevent muscle breakdown after exercise.Bottoms up!  Nutritional supplement beverages can be formulated as an RTD, or a powdered mix to be reconstituted with water, juice or milk. Depending on the target market, they can be formulated as a complete-meal replacer with a full nutritional complement; supplements for one or more important nutrient; or even as weight-management aids.  Stability and organoleptic problems, arising from nutrient levels and ingredient interactions, can make formulation of these beverages difficult. "Several of the minerals - in particular, magnesium, copper and iron - are highly reactive with the casein protein often used in RTD meal replacers," says Audra Davies, director of product development, Watson Foods, West Haven, CT. "They cause coagulation and precipitation of the proteins, which is a stability concern under long-term storage." Hydrating the protein first and then adding the vitamin and mineral premix helps minimize this problem.  The effect depends on the levels used, Davies says. For example, it's preferable to use minerals at a rate of 15% to 25% of the RDI (Recommended Daily Intake) vs. 50% to 75%, because the higher levels add objectionable and difficult-to-mask off-flavors.  A liquid system can be more susceptible to oxidative degradation and this must be taken into account when formulating, says Sam Sylvetsky, director of sales, Fortitech, Schenectady, NY. A dry blend, for example, might require a 10%-to-15% overage, while a RTD beverage can require up to a 100% overage to maintain label levels.  In RTD beverages, heat and pH might adversely affect flavors and nutrients. The greater the time period under high heat, the greater the degradation of heat-sensitive vitamins in the product. Retorting is the most severe heat treatment.  "Processing under UHT (ultra high temperature) for several seconds, or HTST (high temperature short time) at 180(F for 30 seconds, is preferable," says Kevin Mulvehill, manager, food premixes, BASF Corporation. "However, a hot-fill process, usually done at 140° to 160(F, can be beneficial because there will be less dissolved oxygen present in the finished product to cause deterioration."  An acidic product can reduce the temperature or duration required. "A low pH product (pH less than 4.6) requires a less severe heat treatment to kill spoilage bacteria. Also, below a pH of 4.6, the deadly bacteria, Clostridium botulinum cannot survive," Sylvetsky says.  Low pH beverages have become a popular way to deliver extra nutrients. Tropicana Dole Beverages North America Inc., Bradenton, FL, has developed orange juices, fortified with either calcium (35% of RDI) and extra vitamin C (180% of RDI), or with antioxidant vitamins A (as beta carotene), C and E.  Although selection of fortification nutrients is consumer-driven and depends on many factors, a beverage's marketplace success relies on the nutrients delivering taste, functionality and health benefits, says Nancy Green, Ph.D., manager of nutrition at Tropicana. Tropicana's orange juice contains tricalcium citrate because of its good bioavailability and solubility at the pH of this beverage. It also offers a neutral taste. The citrate ions act as a buffer to help maintain the tartness level and also act as a natural preservative.  A mildly acidic environment can help solubilize most minerals and some vitamins, such as folacin, but vitamins A and C show instability at acidic pH levels, Mulvehill says. Vitamin A isomerizes and becomes inactive below pH 6 and the stability of vitamin C decreases below pH 4.2. "Despite pH sensitivity, all vitamins can be included in an acidic beverage if an appropriate overage amount is used and steps are taken to minimize losses during processing."  Through a patented process called "micellization," vitamins A and E can be made water-soluble, according to David Rutillo, Ph.D., vice president, R&D, Bioglan, Laguna Hills, CA. "The oil soluble vitamins are blended with naturally occurring fatty acids and more polar fatty alcohols," he says. "Water is slowly added to this mixture under mild heat. The result is a microemulsion with the oil droplets broken up into smaller particles that cannot be seen by the naked eye." Final particle size is between 0.05 and 0.50 (m.  "The smaller the particle size, the greater the products' water solubility," says Rutillo, noting that the smaller particle size prevents ringing or settling in beverages and does not contribute to cloud formation.  Depending on the target market, these beverages may contain fat. One version - medium chain triglycerides (MCTs) - provide health and functional benefits.  In the body, MCTs are metabolized directly into energy by the liver, rather than being deposited into fat cells; they also are easier to digest. As part of structured lipids, they have been incorporated into a number of enteral products.  "A major advantage in using MCT oil is its high stability against oxidation," says Dilip Nakhasi, food chemist, Stepan Company, Maywood, NJ. "Since all the fatty acids present are saturated and not subject to attack by oxygen, MCT oil can be used at high levels in a performance or meal-replacer beverage without having to add an antioxidant."  "Although MCT oil would not be well-suited for a clear sports drink, because the fat content will contribute opacity, it can be used as a beverage-clouding agent at very low levels without requiring an emulsifier," Nakhasi says. "In this case, MCTs can be claimed on the label without significantly affecting the level of total fat." MCT oil also is colorless, odorless, and possesses a bland flavor and low viscosity.Senior sipping  More than 50 million seniors, older than 50, live in the United States. This segment not only holds significant buying power, but also tends to be quite health-conscious and discerning of the foods they purchase. To successfully tap into this potential, the food technologist must understand seniors' needs and preferences in order to design appropriate beverages.  "It is especially important that a higher flavorant level be used in beverages to target this age group, because older Americans have diminished sensory capacity," says Mary Schmidl, Ph.D., adjunct professor, department of food science, University of Minnesota, St. Paul, MN. Flavor perception involves odor and taste. Ability to distinguish between the four basic tastes doesn't change much during the aging process, but the ability to perceive and identify odors does decrease.  Older persons tend to require fewer calories due to reduced metabolic rates and inactivity. They also may have decreased gastric acid secretion, which lowers iron and calcium absorption. To improve mineral absorption, a highly soluble and bioavailable source should be selected. Calcium citrate, for example, is a good source of calcium because it is highly soluble, has a pleasant taste, and also contains 21% calcium on a formula weight basis. Calcium lactate and calcium gluconate only possess 13% and 9% calcium, respectively.  Dairy products also contain calcium; whole milk contains approximately 1 gram calcium per liter. But dairy-ingredient manufacturers can significantly increase this level. For example, according to Martin Davis, general manager, Davisco Foods International, Inc., LeSueur, MN, the company offers a "fractionated or separated whey product manufactured by a system of mechanical and chemical unit operations that isolate certain components of the whey. From the standpoint of the calcium, it's at a higher concentration - 5% calcium - and the calcium is in the form of a soluble salt. Some preliminary studies support the theory that its bioavailability has been improved with its solubility." Food Product Design takes a look at this study in this month's Portfolio section.   "While 'wellness' beverages for this age group should contain higher levels of vitamins and minerals in their most bioavailable form, current research has not concluded the exact amount that should be added to the RDI," Schmidl says. "However, it is unlikely that the beverage would be the sole supplier of nutrients."  Target fortification levels are typically the same as for younger adults. If the beverage is designed as a significant nutrient source, the protein should supply all essential amino acids and be easy to digest. Some health professionals recommend increasing calcium levels from 1,000 to 1,500 mg per day to help prevent osteoporosis. Since free radicals may accelerate the aging process, Woolf recommends adding antioxidant vitamins C, E and beta carotene - which act as free-radical scavengers -at much higher doses than the current RDI. Although the adult RDI for vitamin E is 30 IU/day, studies indicate levels greater than 150 IU/day improve the health of patients with various states of disease.  Some older Americans are diabetic and require foods that will increase their intake of complex carbohydrates, but not calories. "A complex carbohydrate such as maltodextrin, or a fiber source, like a bland-tasting hydrocolloid," Schmidl says, "can improve the ability of diabetics to process blood sugar, provide mouthfeel, and can be coupled with high-intensity sweeteners, such as aspartame, for improved taste." Aspartame has a sweetness of about 180 to 200 times that of sucrose, and is most stable in beverages at a pH of 3 to 5.Protein power  Currently, the RDI of protein - set by the National Research Council of the National Academy of Sciences - is 2.2 g/kg body weight for infants and 0.75 g/kg body weight for adults. This makes protein an essential component of many nutritionally oriented beverages. Most protein ingredients for beverages are either dairy-based (whey or casein) or soy-based. Proteins possess many characteristics that influence their use in a formulation.  The nutritional value of proteins are now measured by the PDCAAS (protein digestibility corrected amino acid score). This method is based on human amino acid requirements. The old method, the protein efficiency ratio, was based on animal studies. Casein has a PDCAAS of 1.00, soy protein concentrate is 0.99, and soy isolate is 0.92, according to the 1989 Food and Agricultural Organization/World Health Organization Joint Expert Consultation on Protein Quality Evaluation. Specific protein ingredients may vary slightly from these levels.  Whey proteins can be subdivided into four main fractions: (-lactoglobulin, (-lactalbumin, bovine serum albumin, and immunoglobulins. The minor proteins include lactoferrin and the enzyme, lactoperoxidase. Whey protein is easily digestible and contains all the essential amino acids in the proper proportions needed by humans.  Dried whey starts off with about 75% lactose and 12% protein. Depending on the type of cheese from which it is derived, an acid or sweet whey results. Acid whey has a higher mineral content than sweet whey.  Whey can be selectively concentrated to form whey protein concentrate (WPC), which contains 34% to 80% protein (3% to 4% moisture basis); and whey protein isolate (WPI), with a protein content of more than 90% (dry weight basis). The technique greatly influences the protein's composition and characteristics. A number of techniques are used to create these products and they all can result in products with slighly different compositions and characteristics.  Filtration techniques depend on the size and shape of the protein molecule. Different temperatures, pressures and other factors can influence the end product.  "Microfiltration is substantially different from ultrafiltration," says Ewan Ha, Ph.D., director of R&D, Avonmore, Richfield, ID. "Microfiltration permits the separation of protein molecules, based on the size and degree of denaturation. It also eliminates fat. Ultrafiltration does not have these performance characteristics."  "With ultrafiltration, one thing that affects purity is the membrane," points out Davis. "If the membrane starts to foul, the product itself starts to act as part of the membrane. By the very nature, impurities start to collect - lactose, NPN (non-protein nitrogen) and small amounts of fat."  Another technique used to produce WPIs is selective ion exchange. This technique involves separating the protein by electrical charge rather than by molecular size and conformation. "We selectively, in a very defined fashion, control the particular proteins in their original form with this process, so we get the same protein quality and purity every time," says Davis. "We're very confident in the results that show that (this process) isolates the whey protein in its native state."  One of the keys to developing a successful product is the proper selection of the whey protein. "An 80% protein WPC, used at about 3%, would be the proper choice in an infant formula ," says Chao Wu, Ph.D., senior food scientist, New Zealand Milk Products, Santa Rosa, CA, "not only because of its high protein content, but WPC also has about 6% fat, which infants need as a good energy source. It also is cheaper than WPI. WPI would work best in a sports beverage, because its low fat content, at less than 1%, provides excellent clarity in solution."  Whey can be demineralized or heat-denatured for enhanced functionality. Demineralizing whey, using ion exchange resins or electrodialysis, can lower the mineral content to 1% to 2% and yields a final product of superior flavor, with an increase in perceived sweetness and excellent foaming properties. Foaming properties are improved since these whey proteins no longer have to compete with the mineral salts for water, Ha notes. The proteins can swell to their maximum capacity, and by entrapping air, work very well in nutritional shakes and drinks.  The solubility of whey proteins are affected by heat, pH and ionic strength. They are the least soluble at their isoelectric point: pH 4.2 to 4.5 for lactalbumin, and 5.3 to 5.5 for lactoglobulin.  Whey proteins, like many other proteins, exist as highly coiled structures in nature. Heat causes these coils to unfold, reducing the protein's solubility. Whey, and its fractions, are susceptible to denaturation of varying degrees at processing temperatures above 155(F (70(C). Immunoglobulins are the least heat-stable fraction, with (-lactoglobulin and (-lactalbumin showing increasingly greater stability.  However, partially denaturing whey proteins by heating to 50° to 80(C, at neutral or slightly alkaline pH for 10 to 15 minutes, can improve their functional and nutritional properties. This causes a partial unfolding of the protein, exposing hydrophobic regions, which can bind with lipids and help stabilize an emulsion.  "Denatured whey proteins can be easier for infants to digest because the protein is in the unfolded state and more vulnerable to enzymatic attack," Wu says. "Denaturation also causes an increase in the final viscosity, which can add body and mouthfeel characteristics."  Although the whey protein could be added to an acidic beverage anytime during processing, Ha recommends including it before any acidulant is added. This is because whey protein possesses better dispersability and solubility at neutral pH.  Undenatured whey proteins, such as those produced by the mild, natural process of cross-flow microfiltration also contain components exhibiting antiviral and antibacterial properties points out Ha. "One Australian study has shown that whey protein has had a dramatic effect on colon cancer. These are exciting results for the food industry and indicate that dietary whey protein can have a positive impact on health."  Casein exists in several different forms in milk. These are bonded to calcium phosphate in a unique spherical complex known as the "micelle." Caseins exhibit excellent solubility and heat stability above pH 6.0, even at pasteurization temperatures of 180° to 200(F. Caseins also have very good emulsifying characteristics owing to their structure - regions of both hydrophobic and hydrophilic amino acids that can bind compounds at the oil-water interface. Whey and soy proteins lack this amphiphilic structure and are therefore generally less effective emulsifiers.  Casein displays a lack of acid stability in beverages and will precipitate out of solution at a pH of 4.6 - its isoelectric point. In a fruit-juice application, high methoxyl (HM) pectin, a highly negatively charged hydrocolloid, can surround the casein micelle and help to keep the protein in suspension by preventing the formation of casein aggregates, says Sylvia Reisenbigler, marketing communications, Erie Foods, International, Erie, IL.  To be used as a beverage ingredient, the insoluble, acid casein has to be neutralized with the appropriate alkali salt prior to drying, Aoun says. Several different types of caseinates (sodium, potassium, magnesium and calcium) will result with each one having different functional properties.  Sodium and potassium caseinates display similar properties. Both possess higher viscosities, compared to calcium caseinate, and this contributes good body and mouthfeel in meal-replacement beverages. "Because sodium caseinate is very heat-stable and has good emulsifying properties, it is ideal for use in infant formulas, where the fat content is generally higher than for other beverages," Wu says. "Potassium caseinate may be preferred for a low-sodium product."  Although calcium caseinate, like magnesium caseinate, has somewhat less heat stability and less emulsification properties, they provide label appeal and serve as excellent sources of essential amino acids and minerals with high bioavaliability. While calcium and magnesium caseinates would not be ideal in a clear sports beverage because of their "milky" appearance, they are useful in meal replacers where they add whiteness and opacity.  In order to get "the best of both worlds" in a weight-loss beverage or a meal replacer, milk protein isolate or total milk protein (TMP) can be used at levels from 2% to 5%, notes Wu: "TMP is actually a spray-dried, concentrated version of milk, in which both casein and whey proteins are present in their original 80-to-20 ratio."  TMP contains about 90% protein and is produced under mild heating, which partially denatures the proteins. TMP provides a bland flavor and good emulsification properties. While TMP is unstable in a fruit-juice beverage at pH 4.0 because of the casein protein fraction, it is quite stable in meal-replacer drinks with a pH 6.0 to 7.0, Wu says.  Soy protein isolate contains 90% protein, and soy protein concentrate contains a minimum of 70% protein (both on a dry-weight basis), along with soluble fiber. Soy tends to be less expensive than milk-based proteins or hydrolysates, and can be used at levels between 0.5% and 5.0% in beverages. Flavor level, solubility and other characteristics depend on the exact product used. Enzymatically hydrolyzed soy proteins can be formed using a low level of hydrolysis; these are used for emulsification, and to increase viscosity in a beverage.  "For a product that you would disperse in liquid and then drink quickly, one could use an alcohol-wash concentrate, if you weren't looking for soluble functionality of the protein," Gottemoller says. "They are generally quite bland and don't contribute much viscosity. There are other functional concentrates that are just as bland, but they would give a product more viscosity."  Soy isolate can produce a range of viscosities, depending on the product. "For a sports drink, you would probably want a lower viscosity material, but the choice is dependent on a number of factors: the protein content, other ingredients used, and the end use," observes Gottemoller.  In addition to cost advantages, the use of soy protein can enable a product designer to formulate a vegetarian or kosher pareve product. Studies indicate that soy-protein consumption offers numerous health benefits, including reducing heart disease, cancer and osteoporosis. Soy-product flavor has greatly improved over the years, so it will be undetectable in strawberry- or vanilla-flavored beverages.  In addition to the process, the pH of the system can affect the solubility of soy protein isolates. Free calcium will cause soy protein to form a precipitate - the same phenomenon used to form tofu.  The nutritional beverage industry has only just begun to flex its "formulation muscle." A wide range of new ingredients has been developed that will not only add value for consumers, but also provide food processors with enhanced functionality and ease of use. Through the skills of food technologists, these beverages can be specially designed to meet a diverse population's ever-changing needs.Solubility Solutions  Effectively dispersing proteins or putting them into solution in a beverage may prove difficult. The dispersability characteristics of proteins or other hard-to-mix ingredientscan be increased by two methods, which can be used singly or together: agglomeration and instantizing.  Agglomeration fuses smaller particles together to form a larger aggregate. The process was reviewed in "Spray-Drying - Innovative Use of an Old Process" (May 1997 Food Product Design). The larger particle forms an open structure that promotes wetting and also reduces dusting.  Instantizing makes a powder more readily dispersible in water. Protein, a hydrophilic ingredient, can be surface-coated with a lipophilic emulsifier, such as lecithin. "By coating the proteins with lecithin, their interactions with water are slowed down and this helps wet (or hydrate) the protein more evenly, preventing lumping and promoting more even mixing." says Pat Schroder, vice president, ADM Lecithin, Decatur, IL. Hydrophobic, high-fat powders can be treated with a more hydrophilic lecithin or other surfactant that promotes wetting.  Instantizing can be done to nonagglomerated or agglomerated powders. Adding the instantizing agent during the agglomeration process may enhance their instantizing properties.Functional Fibers  Gums or hydrocolloids help to stabilize beverages and also can add to their nutritional appeal. Soluble fibers, such as gums, have been found to cause a lowered glucose response in diabetics, and can also reduce serum cholesterol. Gums also contribute a minimum of 80% soluble dietary fiber, which make this ingredient very "label-friendly."  Gums serve a variety of other important functions in beverages. Carrageenan, a gum extracted from such seaweeds as Irish moss, is protein-reactive and contributes body, even at low levels of between 0.05% and 0.20%. Carrageenan is particularly effective in milk-based beverages since it prevents protein coagulation or "wheying-off" by calcium ions.  Carboxymethylcellulose comes in a variety of different viscosity ranges; it also is protein-reactive and provides excellent clarity. Xanthan gum is an excellent suspending agent for ingredients, such as cocoa particles, vitamins and minerals, and fiber sources like microcrystalline cellulose. Guar, a typically viscous gum, can now be specially processed for use at higher levels in beverages without greatly affecting the flavor profile according to Florian Ward, Ph.D., vice president of R&D, TIC Gums Inc., Belcamp, MD.  "The unpleasant mealy and grassy organoleptic properties, typical of regular guar, have been dramatically reduced to transform this gum into a bland-tasting product," Ward says. "Since mouthfeel and flavor are important sensory attributes for beverages, a reduced-odor guar fits the bill nicely, since it doesn't add any grittiness or graininess and also contributes body without masking the light flavor notes found in some beverages. Because this product is not chemically modified, it provides a clean label and it is also inexpensive."  Gum arabic also serves several key functions in meal-replacer drinks. "Besides being a good emulsifier, arabic can be used at even higher levels than guar, typically 1% to 5% of the total weight," Ward says. "Gum arabic can help foam stabilization and also contributes little viscosity, enabling more soluble dietary fiber to be formulated into the beverage."  These plant gums are water-soluble and it is important for them to be fully hydrated to realize their maximum potential. When using gums, it helps to first blend them with other dry ingredients, such as sugar, and then to add this blend to water under sufficient agitation. Dry-blending the gum helps alleviate the problem of "fish eyes," which occurs during improper mixing when the gum is not properly hydrated.A Cultured Taste  Yogurt has long enjoyed a reputation as a healthy food, and yogurt drinks are becoming increasingly popular, especially among older consumers, according to Wayne Geilman, Ph.D., consultant, Marquez Brothers, San Jose, CA. "Yogurt beverages provide an excellent source of calcium and protein, and are low in lactose, which is beneficial for those who are lactose-intolerant." Most of the lactose sugar - naturally present in milk - is fermented to lactic acid by the bacterial cultures. To sweeten these beverages, a combination of carbohydrates , such as sugar, high fructose corn syrup (HFCS), or corn syrup are used.  "Depending on the DE of the HFCS or corn syrup used, you can vary the body and texture of the beverage considerably, from a low viscosity to a more viscous and syrup-like consistency," Geilman says. "Sugars absorb water to varying degrees and provide different taste and mouthfeel characteristics."  Even the full-fat yogurt beverages with a 3.5% fat content are selling well. This is probably because older Americans are used to the "heavier," full-bodied texture of whole-milk products from their youth, Geilman explains; fat acts as a tremendous flavor enhancer.  Yogurt beverages that contain "live and active cultures" (LAC) may carry the LAC seal from the National Yogurt Association. It cannot appear on a product if the bacteria have been destroyed during pasteurization. "Many health benefits, such as decreased risk of colon cancer, have been attributed to consumption of these probiotic bacteria," Geilman says.Back to top